Jean Piaget

Jean
Piaget(August
9, 1896 - September 16, 1980), a professor of psychology at the University of
Geneva from 1929 to 1954, was a French Swiss developmental psychologist who is
most well known for organizing cognitive development into a series of stages.

For example, he outlines
four stages of cognitive development:

Sensorimotor

Preoperational

Concrete
Operational

Formal
Operational

These
four stages have the following characteristics:

invariant
sequence

universal
(not culturally specific)

related
to cognitive development. but...

generalizable
to other functions

stages
are logically organized wholes

hierarchical
nature of stage sequences (each successive stage incorporates elements of previous
stages, but is more differentiated and integrated)

Piaget's
theory supposes that people develop schemas (conceptual models) by either
assimilating or accommodating new information. These concepts can be explained
as fitting information in to existing schemas, and altering existing schemas in
order to accommodate new information, respectively.

Although
some of Piaget's ideas are similar to those of Lev Vygotsky, Piaget was apparently
unaware of Vygotsky's work. Originally a marine biologist, with a specialization
in the molluscs of Lake Geneva, he embarked on his studies of developmental biology
when he observed the way his infant daughters came to grips with and then mastered
the world around them.

Piaget's
theories of psychological development have proved influential. Among others, the
philosopher and social theorist Jürgen Habermas has incorporated them into his
work, most notably in The Theory of Communicative Action.

Piaget
also had a considerable impact in the field of computer science. Seymour Papert
used Piaget's work while developping the Logo programming language. Alan Kay used
Piaget's theories as the basis for the Dynabook programming system concept, which
was first discussed within the confines of the Xerox Palo Alto Research Center,
or Xerox PARC. These discussions led to the development of the Alto prototype,
which explored for the first time all the elements of the GUI, or Graphical User
Interface, and influenced the creation of all of the user interfaces which were
to appear in the 1980s, the 1990s and beyond.

Piaget
authored of The Child's Conception of the World (1926), The Origin
of Intelligence in Children (1936), The Early Growth of Logic in the
Child (1958).